1) Field of the Invention
The present invention relates to the forming of sheets and, more particularly, an apparatus and method for forming corrugated contours in a sheet of material such as metal.
2) Description of Related Art
Corrugated sheets are widely used for a variety of applications. For example, metal structural panels used in vehicles, buildings, and containers can be corrugated to provide an increased resistance to bending or buckling relative to flat sheets. Corrugated webs can also be used to form structural components such as beams. A corrugated web beam, for example, includes a corrugated web that extends between top and bottom flanges, and can be used as a beam or column for constructing a larger assembly.
The cross section, or profile, of a corrugated sheet typically defines continuous wave-like sinusoidal contours. The rigidity and other structural characteristics of the sheet are determined, in part, by the shape of the sinusoidal contours, including the xe2x80x9cwavelengthxe2x80x9d and xe2x80x9camplitudexe2x80x9d of each contour. Thus, it is often desirable to produce corrugated sheets having different profiles for different applications. According to one conventional method of forming corrugated sheets, a flat sheet of material such as steel is stamped between a pair of cooperable dies that define the corrugated contours. A corrugated sheet that is longer than the dies, i.e., defines a greater number of corrugations than provided by the dies, can be formed by repeatedly advancing the sheet so that a flat or unformed portion of the sheet is disposed between the dies and stamping the sheet therein. However, in order to form sheets with different profiles, the dies must be changed. Therefore, different dies are required, and an operator must stop the formation process and change the dies to change the profile, increasing the cost and time required for forming the corrugated sheets.
Thus, a need exists for an apparatus and method for forming corrugated sheets such as sinusoidal sheets formed of metal. The apparatus should be adaptable to provide sheets with different profiles, while operating with minimal interruptions to increase output and minimize cost. Preferably, a minimum number of profile-specific dies or other components should be required.
According to one embodiment, the present invention provides an apparatus for forming a corrugated contour in a sheet. The apparatus includes at least three pairs of elongate dies, such as cylindrical rolls, that extend in a longitudinal direction. The dies of each pair are generally parallel and define a nip therebetween so that the sheet can be moved successively through the nips for forming. Each pair of dies can be actuated in successively opposed directions generally perpendicular to a direction of motion of the sheet to thereby form corrugated contours in the sheet. The dies can be extended by differing distances to form contours of different heights in the sheet. Further, each pair of dies is adjustable in a transverse direction generally parallel to the direction of motion of the sheet so that an offset distance between each successive pair of dies can be adjusted. For example, each die can be connected to a track that extends generally in a direction parallel to the motion of the sheet. The longitudinally opposed ends of each die can be adjustable by differing distances in the transverse direction so that the dies can be configured at relative angles, and a controller, such as a programmable logic controller, can be provided for adjusting the dies according to a desired configuration of the sheet. The apparatus can also include a heater for heating the sheet to a forming temperature.
The present invention also provides a method for forming a corrugated contour, such as a sinusoidal contour, in a sheet. The sheet can be formed of a variety of materials such as aluminum or titanium and can be heated before forming. The method includes providing at least three pairs of the elongate dies, adjusting the dies in the transverse direction to adjust the offset distance between each successive pair of dies, advancing a sheet of material between the dies of each pair so that an unformed portion of the sheet is disposed therebetween. The dies are actuated in successively opposed directions generally perpendicular to the direction of motion of the sheet to thereby bend the sheet and form at least one corrugated contour.
The sheet can be repeatedly advanced and the dies actuated to selectively form multiple corrugated contours in the sheet, and the dies can be adjusted between each successive actuation so that a length of the corrugated contours differs throughout the sheet. Further, the ends of each die can be adjusted transversely by different distances to configure the dies at relative angles and form the contours at an angle oblique to the direction of motion of the sheet. The dies can also be extended by differing distances so that the height of the contours differs throughout the sheet. According to one embodiment, a list of control instructions are stored in a memory device and retrieved for use by a controller that controls the apparatus.